1. Field of the Invention
The present invention relates to a heat sink fan for cooling electronic components such as a micro processing unit.
2. Description of the Related Art
A heat sink fan that is attached to a heat-generating electronic component such as micro processing unit (MPU), usually includes a heat sink that is placed on the MPU and a fan case that is attached to the heat sink and houses a fan for forcedly cooling the heat sink by blowing air thereto. The heat sink that is used for such heat sink fans, which is conventionally made of high heat conductive material such as an aluminum or the like, is made by a die-cast molding. However, a heat radiating fin, which is integrally formed with the heat sink for dissipating heat generated by the electronic component, is restricted on thickness and shape, if the heat sink and the heat radiating fin are made by die-cast molding. Consequently, the heat sink fan using the heat sink made by the die-cast molding cannot sufficiently cool the MPU generating large amount of heat. Therefore, an improved heat sink is proposed, in which thin heat radiating fins formed by press working are fixed to a base member made of a copper, a cooper alloy or the like by crimping the fins fitted in grooves formed on the base member. Such heat sink has some advantages. First, because thickness of each heat radiating fin can be small, the number of heat radiating fins arranged per unit area of the base member can be increased. Secondary, the heat radiating fins can be made of a material different from the base member. Accordingly, such a heat sink can increase the heat radiating surface and/or dimension compared with the conventional heat sink made by the die-cast molding and large amount of heat can be radiated, therefore, the cooling efficiency of the entire heat sink can be improved dramatically.
However, such a thin heat radiating fin is easily deformed by an external force, because the thickness of each heat radiating fin is small. Particularly, if a heat sink fan is attached to an MPU by using an attachment member such as a clip or fastener that utilizes elasticity, the fan case, which is generally made of a resin material, is deformed by stress of the clamping force of the attachment member. The deformed fan case presses the heat radiating fin and the heat radiating fin is deformed. The deformation of the thin heat radiating fin may change an air flow induced by the fan or may cause interception of the air flow so that cooling performance or effect of the heat sink fan is deteriorated.